Wellbores are drilled into the earth for a variety of purposes including tapping into hydrocarbon bearing formations to extract the hydrocarbons for use as fuel, lubricants, chemical production, and other purposes. In order to facilitate characterization of a subterranean formation and the fluids contained therein, it is often desirable to lower a NMR logging tool into a wellbore.
Modern NMR well logging instruments and core analysis instruments are capable of acquiring a large amount of data with different acquisition parameters and pulse sequences. The raw data recorded by NMR logging tools are a series of spin-echo amplitudes (echo trains) as a function of time, usually at fixed or predetermined time increments (bins). The evolution of NMR signal amplitudes acquired with these variations of parameters and pulse sequences is often described in terms of NMR characteristic parameters, such as spin-lattice relaxation time (T1), spin-spin relaxation time (T2), and molecular diffusion (D). These NMR characteristic parameters (T1, T2, and D) can be related to reservoir rock properties, fluid phase saturations and distributions, and hydrocarbon storage and producibility information.